Widely known are methods of extinguishing a fire providing introducing into the zone of burning of fire extinguishing agents--liquid, gaseous, powders and flame inhibiting aerosols. Variety methods and means are known for introducing said agents into the center of burning.
However, as the practice of struggle with fire of complex category shows, application of these fire suppressing agents separately does not result in effective extinguishing. The reason for this is that, the majority of fires are of a complex physicochemical process, in course of which, as a rule, there is occurring burning and oxidation of materials subject to burning both in so-called gaseous phase accompanying with formation in the focus of burning of seen flame, and in so-called condensed phase, when the material subject to burning burns so to say from inside, with destruction of its internal structure, but without a seen flame of burning. Thus it is necessary to emphasize, that such fires are accompanied with long period of smoldering of products of burning both during the flame burning and during the long period after it A classical example of such burning is burning of cellulose containing materials such as wood, fabrics, cotton products and other, i.e. materials widely used in all branches of industry and transport.
A method of fire extinguishing is known from the European patent EP 0 561 035 which comprises the following stages: preliminary arrangement in the protected volume of a means for extinguishing a fire containing a first reagent consisting from potassium perchlorate or potassium nitrate or mix thereof, and a second reagent containing epoxy resin; in case of fire it is activated reaction between the first and the second reagents in result of which they interact with formation of dry powder of firm particles in suspended condition (aerosol), these particles have diameter not exceeding 1 micron; said aerosol is cooled, flame is suppressed with help of said aerosol, thus there is occurring chemical and physical suppression of chain reactions of the flame in the center of burning, which results in extinguishing of the fire. In other words, into the center of burning it is introduced a flow of flame inhibiting aerosol which concentration exceeds concentration sufficient for interruption of chain reactions of the flame, Mat results in liquidation of the flame in the center of burning.
The above described method of extinguishing a fire is rather effective for burning materials or agents which are not accumulating thermal energy in their internal structure. Such fires seldom occur in practice. The reason for this is in that, this method of fire extinguishing is based on application of a flame inhibiting aerosol which interrupts chain reactions of the flame just in the gas phase of the center of burning, but, that is necessary to emphasize, does not influence the reactions proceeding in its condensed phase. It means, that with liquidation of flame burning, smoldering of products of burning will keep on, in other words fire will proceed in most dangerous, latent form, at which the seen attributes of fire are not present, but probability of sudden repeated ignition is rather high It is necessary to emphasize that this process is accompanied by hidden accumulation of thermal energy both as a result of smoldering of products of burning and due to increase of concentration of products of burning in the center of burning, e.g., because of falling half burned constructions in the center of burning or due to distribution of smoldering deep into the initial material of burning. It results in gradual, sometimes imperceptible for human, increasing of temperature up to critical level, when flame ignition will be resumed. It is necessary to emphasize that this process is of uncontrolled spontaneous character, therefore it is very dangerous in itself.
The same European patent EP 0 561 035 discloses a plurality of generators for extinguishing a fire embodying the above described method Each of said generators comprises a hollow case, a charge of flame inhibiting aerosol, placed in the hollow of said case at one of its face walls, an initiating means for actuating the generator arranged in said charge and capable to receive starting command signals, a cooling means of the flow of flame inhibiting aerosol, placed in said case of the generator and a cavity formed between said charge and said cooling means.
In this patent there are-described several embodiments of the cooling means of the flow of flame-inhibiting aerosol. For example, on FIGS. 1, 4, 5, 6 and 7 this means is shown as a capacity with cooling liquid. At combustion of the charge-it is formed a flow of flame inhibiting aerosol that is being exhausted from the generator, due to creation of underpressure in the cavity of the case it captures and atomizes in the flow particles of the cooling liquid, as it is shown on FIG. 1 and 4, or aerosol is bubbling in the cooling liquid, as it is shown on FIG. 5, 6a, 7a, resulting in cooling of the aerosol flow.
It is necessary to accentuate, that temperature of the flow of the flame inhibiting aerosol before cooling is on the order of 1000.degree. C.-1200.degree. C., and it is a precondition of physicochemical interaction of the aerosol flow with the cooling liquid, that results in dissolution of aerosol particles in the cooling liquid and in evaporation of the cooling liquid, as well as in chemical transformation of the agents comprising the aerosol, e.g., potassium carbonates into hydrocarbonates. These factors reduce concentration of aerosol firm particles in the flow, that is released from the generator and leads to degradation of its fire suppressing activity. Thus, efficiency of the released flow of aerosol and the generator as a whole will be reduced. Similar processes occurring when a cooling gas or a cooling powder is used instead of cooling liquid, as it is shown on FIG. 3 and on FIG. 4.
Closest to the claimed generator is the fire extinguishing generator disclosed in the description of the Russian Federation Patent Application 94 002970, presented on FIG. 8 and containing a case; a cavity formed in the case; a first face wall of the case; a second facewall of the case; a lateral wall of the case connected by its first end face and its second end face with, correspondingly, the first face wall and the second face wall; the central partition formed in the cavity of the case and fixed on the edges on the case lateral wall; a first chamber formed from the side of the first face wall and delimited by the central partition, the first face wall and the lateral wall of the case; a second chamber formed on the side of the second face wall and delimited by the central partition, the second face wall and the lateral wall of the case; a charge of the flame inhibiting aerosol, installed in the first chamber at the first face wall and intended for producing of the flow of the flame inhibiting aerosol; a first empty cavity formed in the first chamber between the charge of the flame inhibiting aerosol and the central partition; an initiating means for actuating the generator placed in the charge of the flame inhibiting aerosol and capable to receive starting command signals; an additional partition installed in the second chamber and fixed by the edges on the lateral wall of the case; the second empty cavity formed in the second chamber and delimited by the central partition, the additional partition and the lateral wall; a third cavity formed in the second chamber and delimited by the additional partition, the second face wall and the lateral wall of the case; a charge of fire suppressing agent placed in the third cavity; a first set of channels formed in the central partition and intended for passing of the flow of the flame inhibiting aerosol from the first chamber into the second empty cavity; a second set of channels formed in the additional partition and intended for passing of the flow of the flame inhibiting aerosol from the second empty cavity into the third cavity filled by said charge of the fire suppressing agent; a nozzle formed in the second face wall of the case and intended for passing of the flow of the flame inhibiting aerosol and the fire suppressing agent from the third cavity into said center of burning.
In comparison with the generator described in the European Patent EP 0 561 035, the generator disclosed in the Russian Patent Application 94 002970 has that feature, that a fire suppressing powder is used as the fire suppressing component, concentration of which in the flow outflowing from the generator with the lapse of time decreases and concentration of the flame inhibiting aerosol proportionally increases, in result of this it is formed environment of the fire suppressing powder atomized in the flame inhibiting aerosol. Environment of the fire suppressing powder atomized in the flame inhibiting aerosol allows to extinguish smoldering products of burning hat in comparison with the pure aerosol method of fire extinguishing, disclosed in the European Patent EP 0 561 035, expands sphere of application of such generators.
However, the practice of using of such generators and fire suppressing environment showed, that it is quite effective only for extinguishing of smaller centers of burning where there are present both gaseous and condensed phases of burning of the burning products. It is specially effective in case of absence of the gaseous phase of burning accompanied by intensive convective flows of gaseous products of burning.
In case of large fires, fires of complex category, when there are present intensive convective flows, it occurs intensive carrying away of the powdery fire suppressing agent from the surface of burning which has not reached it. It is specially characteristically for the first stage of feeding into the center of burning of the fire suppressing powder, when its concentration is maximal. Besides, a drawback of the described generator is interaction of the flame inhibiting flow of aerosol having temperature 1000.degree. C.-1200.degree. C. with the fire suppressing powder. In fact it occurs partial decomposition and sintering of the fire suppressing powder, that results in loss of its efficiency, in decreasing of effective amount of the fire suppressing powder reached the center of burning, in other words, it occurs its partial deactivation. Simultaneously it also occurs loss of the aerosol, as the thermal decomposition of the fire suppressing powder is accompanied by formation of a liquid-viscous consistence in it capable to catch firm particles of aerosol from the flow. The initial precondition of all these drawbacks is high temperature of the flame inhibiting flow of aerosol which is developed in result of ignition and subsequent burning of the charge generating the flame inhibiting aerosol.